Loading system for telephone lines



Jul 1 y 927 H. JORDAN LOADING SYSTEM FOR TELEPHONE LINES Filed March 15, 1925 2 Sheets-Sheet 1 f2? ventor' Hans Jordan, by

MS A'Ctorhey.

l Ju y 26 1927 H JORDAN LOADING SYSTEM FOR muzmoua mans Filed March 15, 1923 2 Sheets-Sheet 2 I Inventor:

- Hans Jordan, by f/l's Attompey Patented July 26, 1927.

HANS JORDAN, OF KARLSHORST, GERMANY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

LOADING SYSTEM FOR TELEPHONE LINES.

Application filed March 15, 1923, Serial No. 625,369, and. in Germany March 28, 1922.

In the construction of phantomed telephone lines, it is necessary to insert coils in the lines in such manner that a desired degree of inductance is eifective in each of the three combined speaking circuits; that is, in the two main lines and in the phantom line. The resistance of the lines should at the same time be increased as little as possible. Further, care should be taken that, by the insertion of the coils, no disturbances of the mutually connected lines and of the adjacent lines are occasioned.

In the arrangements of coils which have mainly been employed heretofore for this purpose, by any method of operation of the lines only a small part of the windings has served the intended purpose. The other very considerable part was not only ineffective, but was even harmful by reason of the resistance of its turns.

Devices in which several windings belonging to separate circuits are combined into one coil tend toward the mutual disturbance of the mutually connected circuits. Such devices, therefore, require special precautions for preventing disturbances, and are therefore diflicult and costly to make.

Among other devices known, the combining of the two duplex coils, into one coil has the disadvantage, besides that of the deadv turns, of complicated equalization as regards mutual disturbances.

By certain proposed arrangements which obtain the loading of the multiplex line by magnetic concatenation of the main coils, the dead turns are avoided. But in such arrangements special precautions are re quired in order to obviate the mutual disturbances. This arrangement also becomes thereby complicated to produce.

The object of the present invention is to provide a loading system which will be free from these disadvantages. The self-induction coils of my invention permit not only an improvement in the properties of the conductor and a saving in materialand space, but their manufacture is also much simpler, and therefore cheaper, than that of the types of coils heretofore known for the simultaneous loading of main and duplex lines.

The novel features which I believe to be characteristic of my invention are pointed out with particularity in the appended claims. My invention itself however both as to its organization and method of operation will best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1' shows diagrammatically the general type of telephone system to which my invention may be employed; Figs. 2 and 3 are diagrammatic representations of single coil windings illustrating the manner in which coils suitable for carrying out my invention may be constructed; and Figs. 4 and 5 are diagrammatic representations of two different forms of loading systems with which my invention may be employed.

In Fig. 1 is shown a known and frequently employed system of connections by which on each of the two main lines 1 1 and 2, 2 which serve as main circuits, two subscribers T T and T, T communicate, and on the phantom circuit formed from the main circuits two subscribers T, T? communicate.

The lines are equipped with, in all, four coils at each of the'coil points P P etc. The coils S of the same kind serve for loading the main circuits, and the coils V of the same kind serve for loading the phantom circuit. Each coil carries two like windings, which may be wound in the same sense. The windings and IV? of coils S are connected in the same direction as regards the currents in the corresponding main circuit, and the windings and W of the coils V are connected in opposite directions, so that the magnetic fields created by a current in the main circuit are intensified in the coils S and are weakened'in the coils V. In Fig.

1 the windings are, for the sake of clear-- ness, shown in a manner as if each of them covered onehalf of the annular vironco re. In reality, each winding is distributed over the entire periphery of the ring. Then the fields of the two windings neutralize each other in the coils V if a current is created in the corresponding circuit, and so do the fields of the two windings of the coils S, if

a current is'produced in the phantom circuit. In both cases, however, an unnecessary resistance remains in the circuit, by reason of the ineffective turns. i

The present invention makes itpossible to reduce the dead resistance to a minimum without the necessity at the same time of making provisions for the'equalization of alternating effects by the combination of a considerable number of windings in one coil element.

coils are traversed by currents of the main circuit or the phantom circuit, the fields of W audit. will always be oi opposite direction Since here also, r01.- the sake of clearness in the drawing, the windings cover only ];iart of the ring, but in reality each of the four windings covers the entire ring, only the difference of the numbers of turns of and Vi has any effect. ith respect therefore to the field actions and the resulting i'nductances for all systems of connection, a pair of coils S, V (Fig. 1) may be replaced by one: individual coil in accordance with Fig. 3. Let N5 be the total number of turns of the coil S (Fig. 1), his the total number of turns of the coil V (Fig. 1),

and it may then be assumed according to the ratios of most of the. lines heretofore constructed that his is greater than No. It moreover the same cores are assumed for the coils in Fig. I and for the coil in Fig. S3 there will be in the coil of Fig. 2 in the a-Wire Ns Ne 7*? turns, and in the b-Wire Ns No i effective turns. The entire coil of Fig. 2

efiective turns, that is, only as many turns as in Fig. I one of the two coils carries, namely, the coil S.

The coil of Fig. 3 is unsymmetrical with relation to the two winding portions. In order, on the one hand, to utilize the advantages of this kind of winding, but on: the other hand in order to maintain the symmetry of the main. lines, such coils may, according to the invention, he used on one of the two systems of connections shown in Fig. i and Fig. 5 in which the lines, the subscribers and the coil points are desig nated as inFig. 1.

According to Fig. t one of the coils shown in Fig. 3' situated in eachof the two successive coil points P and P in each main line, but in such manner that in one conductor a winding with a large number of in Fig. 2 that the turns and a winding with a small number of turns always follows each other. In using the -foregoing arrangement, it is to be observed ththose portions oil the-line between successive loading points should be so designed that undesirable effects produced in the propagation of the Waves through any such part of the line shall not he perceptible in that part. Under such conditions, it is suthcient it the actual balance of the line is reestablisl'ied at the successive loading points by the alternate posi tion of the coils. Thus, at any point in such a line the currents in the two conductors are equal in amount so tar as practical effects are concerned. For acalculation of the eli'ective inductance it follows from the above that it is given, as in symmetrical coils, by the number ot turns, regard being had to the direction of rotation of the current.

In special cases. say in the case of short lines with a small number of coil points, it it be assumed that sutiicient symmetry is not established by the arrangement of Fig. t, the arrangement shown in Fig.- 5 may" be adopted in accordance with the invention. in Fig. 5 a phantomed liners shown in which the inductance of the coil wound in accordance with 3 for each (Fig. l) is distributed between two like coils which are connected in such manner in a main line that a winding? of a higher and one of alower numberot turns is connected in every conductor. In this vary the desired symmetry is established at each in dividual coil point. This arrangement also brings very substantial advantages over the connections of Fig. 1, although "four coils are used for each coil point. i

It will be obvious at once from a consideration of Figs. 2 and 3 and the discussionabove given that there is a large reduction in the nui'nber' of turns 0t wire in loading coils necessary at any given loading point and that there is accordingly a large reduction in the dead resistance of the circuit. here it is possible to use the coils in the arrangement shown in Fig. 4 the reduction in. the number of turns and in the total resistance is, of course, larger than. in the arrangement shown in Fig. 5, but even with the arrangement of Fig. 5 the decrease in the number of turns in the loading coils represented at any loading point is obvious. The saving in coils amounts to from 30% to 50%,. depending on the character and condition of the lines.

With a reduction of the number of turns, the size of the cells will generally be reduced also, and thereby material and space will be saved Without greatly impairing the properties ofthe cells. If there is no necessity for reducing. the resistances resulting from the arrangement according to Fi 1,

coil point then further very great savings in material and space will be obtained. In addition to the above mentioned advantages it may be pointed out that with this invention only one type of coil is ever used or one kind of conductor wire, and each coil carries at most two windings, one with a greater and one with a smaller number of turns.

It is known that the coils. even when made Very carefully as regards observing the proportions of the core and the numbers of turns, do not at first prove as uniform as must be required with a view to the charac ter of the conductor wire. On the contrary, repeated measurements are necessary for equalizing the inductances by winding or unwinding turns. This results in a considerable number of working processes, the number of-which operations increases with the number of thewindings, so that multiple coils involve special requirements in this respect. That the equalization is still more difficult as regards mutual disturbances, has already been stated. Also in the case of coils according to Fig. 1, the individual windings have often been divided up and thereby the number of equalizing operations have been further increased. The coils ac cording to the invention have only one winding with a large number of turns, in which small variations, say, in the proportions and the properties of the cores may exert a great influence on the inductances to be attained. The same per cent of faults in the small supplementary winding has however a correspondingly smaller influence on the total re sult. Thus only the winding having large numbers of turns will require equalization, and there is no reason for dividing this winding. Moreover the supplementary winding may be placed over the main winding, and the capacity between the two windings may be reduced in a manner already known in itself by means of suitable intermediate layers, since thereby, with the small number of turns, the total length of wire will be only slightly increased.

Vhat I claim as new and desire to secure by Letters Patent of the United States, is,

1. A loading system for phantomed telephone lines comprising coils, each of which has two windings of unequal number of turns, the sum of the number of turns in the two windings being such as to give the desired inductance for the main circuit when the two coils are connected in opposite sides thereof and act in the same sense, and the difference in the number of turns of the two windings being such as to give the desired inductance for one side of the phantom circuit when the two coils are acting in opposite senses in the two conductors constituting one side of the phantom circuit.

2. A loading system for phantomed telephone lines comprising coils, each of which has two windings with a different number of turns, the numbers of turns of the two windings being so proportioned that the number of turns which in the operation of the line contribute only to the resistance of the line without supplying inductance thereto is reduced to the minimum, at least one such cell being connected with a separate winding in each side of the main line at each coil point and the successive coils being so connected in the line that windings having the greater and smaller number of turnsfollow each other alternately.

8. A loading system for phantomed tele- 7 phone lines comprising coils, each of which has two windings with a different number of turns, the numbers of turns of the two windings being so proportioned that the number of turns which in the operation of the line contribute only to the resistance of the line without supplying inductance thereto is reduced to the minimum, two such coils being connected in series, with a separate winding in each side of the main line at each coil point, a winding having the larger number of turns being connected in series with a winding of the smaller number of turns. 7

In witness whereof, I have hereunto set my hand this 15th day of February, 1923.

HANS JORDAN. 

